Male Reproductive System
Male Reproductive System
Objectives
· Identify and give functions of all components of male systems
· Describe the composition of semen and its functions
· Identify the three regions of the male urethra
· Identify the structures and tissues of the penis
· Describe the process/pathway of sperm and development of semen
Male Reproductive Anatomy
The male reproductive system consists of a pair of testes, conducting ducts, accessory glands and the penis
Testes
[Section 27.1: Anatomy and Physiology of the Male Reproductive System]
[Figure 27.2: Male Reproductive System; Figure 27.3: The Scrotum and Testes]
· paired, separated by the Dartos muscle
· Produces spermatozoa and testosterone (interstitial cells)
· Lies in the scrotum outside the abdominopelvic cavity where the temperature is slightly lower than inside the body. The lower temperature optimizes the rate of sperm production
· Each is covered by a dense connective tissue capsule called the tunica albuginea(“white tunic”)
o Inward extensions of the tunica albuginea divide the testes into lobes containing seminiferous tubules
§ These tubules produce millions of spermozoa a day
Conducting System
[Section 27.1.4: Sperm Transport]
[Figure 27.2: Male Reproductive System; Figure 27.4: Anatomy of the Testes]
Epididymis, vas deferens, ejaculatory duct and urethra form a system of tubules for the transport of spermatozoa from testes to the pelvic cavity. There they will be combined with the secretions of the accessory glands to form semen.
Epididymis
[Section 27.1.4.1: Role of the Epididymis]
[Figure 27.2: Male Reproductive System; Figure 27.4: Anatomy of the Testes]
· An elongated structure on posterolateral surface of testis that caps on the superior side.
· First portion of duct system
· Provides site for maturation of sperm
Ductus Deferens (Vas Deferens)
[Section 27.1.4.2: Duct System]
[Figure 27.2: Male Reproductive System; Figure 27.4: Anatomy of the Testes]
· upon ejaculation, sperm is received here from the epididymis by peristalis
· passes through the inguinal canal into the pelvic cavity and superiorly over the bladder
· enclosed with spermatic cord (a connective tissue sheath consisting of blood vessels, nerves and the cremaster muscle. This muscle encases the testes & elevates or lowers them to maintain the temperature needed to create sperm.
· end is enlarged (called ampulla)
· empties into the ejaculatory duct
Ejaculatory Duct
· During ejaculation, its contraction pushes sperm through the prostrate and to the prostatic urethrawhere it joins the seminal vesicle
Urethra
· from the prostatic urethra, sperm travels through the membranous urethra and then into the spongy urethra that runs the length of the penis.
Accessory Glands
Three accessory glands produce seminal fluids that nourish, protect and support the spermatozoa
Combined with spermatozoa from the testes, these fluids form the ejaculate or semen
Each gland contributes a certain percentage to the total volume of semen
Seminal Vesicles
[Section 27.1.4.3: Seminal Vesicles]
[Figure 27.2: Male Reproductive System]
· produces 60% of seminal fluid
· lie close to end of ductus deferens
· produce an alkaline secretion made of fructose and other fluids that provide ATP for the motion of the sperm tail and promotes fertility.
· duct merges with duct of ductus deferens to form ejaculatory duct (this allows sperm and seminal fluid to enter urethra together)
Prostate
[Section 27.1.4.4: Prostate Gland]
[Figure 27.2: Male Reproductive System]
· 20-30% of fluid
· circles around urethra and secretes a milky fluid that coagulates semen.
· This works to help activate the sperm
· Because it encircles the urethra, if the prostate becomes enlarged due to cancer or other facts, men will have a difficult time urinating
Bulbourethral Glands
[Section 27.1.4.5: Bulbourethral Glands]
[Figure 27.2: Male Reproductive System]
· produces approx. 5% of fluid
· pea shaped and very small
· produce thick, clear alkaline secretion mucus that drains into the membranous urethra
· this secretion is to intended to wash any urine out of the urethra when ejaculation of semen occurs as well as act as a buffer to the female reproductive tract (which is an acidic environment.)
· alkalinity neutralizes acidity of the male urethra and female vagina
Penis
[Figure 27.2: Male Reproductive System; Figure 27.7: Cross-Sectional Anatomy of the Penis]
· The penis is the male copulatory organ.
· External (along with scrotum)
· Designed to deliver sperm to the female reproductive tract. (The spongy urethra transports both urine and semen through the penis)
· Consists of three main parts:
o shaft/body
o glans (large tip of the shaft)
o prepuce/foreskin (loose skin of the penis which covers the glans and is often removed by a process called circumcision)
· The body of the penis consists of 3 cylinders of erectile tissue
o A pair of corpora cavernosa on the dorsal side
o A single corpus spongiosum on the ventral side
· During sexual arousal, the three cylinders become engorged with blood, causing an erection